The LED (Light Emitting Diode) technology has been widely promoted for the advantages of power saving, high brightness, long service life, and good seismic performance. In recent years, LED lights have become more and more widely used in daily lighting and displays. The more common applications, such as LED lamp panels, that is, a plurality of LED lamp caps are arranged in an array in a lampshade, and the corresponding drive circuit is provided in the lampshade, the structure is simple and practical, but LED lamp panels are comparatively dazzling and the uniformity of the emitted light is poor (uniformity<70%) because LED lamp panels use direct type light source. Therefore, a kind of LED flat lamps have been developed, which is square flat shape, and the inner parts of the kind of LED flat lamps are flat shape, the flat reflection layer, light guide layer and diffusion layer are installed in a rectangular outer frame successively, and LED lamp bars are installed in the rectangular outer frame and at the side edge of the light guide layer, the light is subjected to multiple reflections under the combined effect of the reflective layer and the light guide layer to improve uniformity and effectively prevent glare through the diffusion layer. The kind of LED flat lamps emit light and generate heat during operation, and the LED flat lamp is easily deformed and damaged based on the principle of thermal expansion and cold contraction if the generated heat cannot be released in time, which shortens the service life.
In addition, the flat lamp in the prior art has the following problems:
1. The diffusion plate uses the same material, such as: PS (polystyrene)\PMMA (polymethyl methacrylate)\PC (polycarbonate)\PET (polyethylene terephthalate)\PP (poly Propylene\PE (polyethylene), etc., but not limited to these materials, PS\PMMA\PC\PET has good flatness but is a hard material, and PP/PE material is soft, deformable and not flat enough thereof. The conventional light guide layer is also made of the same plastic material, such as PS\PMMA\PC\PET, but not limited to these materials. In the design of the conventional flat lamp and surface light source product, the light guide layer and the diffusion layer are tightly attached to each other. If the light guide layer and the diffusion layer are made of the same material, the light-emitting surface of the light guide layer gets easily damaged, which cause the light guide layer to be scrapped. Therefore, the diffusion layer and the light guide layer of the flat lamp and the surface light source product in the prior art are basically made of same material, if PS\PMMA\PC\PET materials with better flatness and hardness are adopted, the light-emitting surface of the light guide layer may get easily damaged, which cause the light guide layer to be scrapped; if softer material like PP\PE is adopted, the diffusion layer gets deformed easily and has poor flatness, and the diffusion anti-glare effect is influenced;
2. The normal service life of the conventional flat lamp is often reduced due to the damage of the LED lamp beads, and the main reason is that two LED lamp bars loaded with several LED lamp beads in the flat lamp are oppositely arranged on opposite sides of the light guide layer, heat is generated while the LED lamp beads emit light after the flat lamp is turned on, and the light guide layer expands to the periphery when heated, therefore the LED lamp beads on the two sides of the LED lamp bars are extruded, which causes damage of the LED lamp beads badly, and shortens the service life of the whole LED flat lamp;
3. The light guide layer is not suitable for large size production due to process problems, the light guide layer can only be spliced in the manufacturing process of large-scale LED flat lamp, but this way of splicing the light guide layer has the following defects: there are light seams in the junction of the light guide layer due to light leakage and unevenness, which not only affect the aesthetic appearance of the whole flat lamp, but also affect the uniformity of light emission, this defect affects further development of the large-scale LED flat lamp market and become the main reason that restrict the market domination rate ascension.
The large-scale flat lamp also has the defects that the light source is integrated with the lamp, if the light source is damaged, replacement is not easy and the replacement cost is high. Besides, the large-scale flat lamp also has poor light uniformity and poor utilization efficiency.
In addition, the light guide plate is an optical grade acrylic PMMA (polymethyl methacrylate)/PS (polystyrene)/MS (polyacrylate)/PC (but not limited to the above material) plate, with the characteristics of extremely high reflectivity and non-absorbing light, and is widely used in LCD (Liquid Crystal Display) and LED (Light Emitting Diode) displays. The light guide plate uses the optical grade acrylic plate to absorb the light emitted from the lamp, when the light hits each light guide point, the reflected light will be diffused at each angle, and then the reflected light will be emitted from the front of the light guide plate. Through a variety of light guide points of different densities and sizes, the light guide plate can be uniformly illuminated, and the line light source can be converted into the surface light source.
Most of the current wedge-shaped light guide plates are manufactured by injection molding, and the principle is that optical grade PMMA/PS/MS/PC (but not limited to the above materials) particles are injected into a mold to be cooled and molded by an injection molding machine at high temperature and high pressure. Generally speaking, injection molding wedge-shaped light guide plate is easy to produce burrs and irregular shapes, resulting in uneven stress, poor flexibility, easy to break down when bended, and low brightness, low product yield rate, especially a very high mold cost, it is necessary to reopen different molds as long as inclined plane angle or product size is changed, mold cost is extremely high and the change becomes very troublesome.